Dual action lift spring



June 12, 1956 c. w. ALDER 2,749,570

DUAL ACTION LIFT SPRING- Filed March 17, 1954 //\/ME/\/ 757/? CLAYTON w. ALDER 7 7- TUF/v/a United States Patent ()fifice 2,749,570 Patented June 12, 1956 DUAL ACTION LIFT SPRING Clayton W. Alder, Camas, Wash.

Application March 17, 1954, Serial No. 416,866

2 Claims. (Cl. 16-198) This invention relates generally to torsion springs and to mechanisms in which such springs constitute an element. It relates specifically to a dual action lift spring and also for providing a change in the action of the governing device in various parts of its movements.

The main object of this invention is to provide a clamp whereby a predetermined portion of a spring may be deprived of its action through all or a portion of the operating time of the remainder of the said spring.

The second object is to construct a torsional spring unit which can be made to meet a wide range of operating requirements without the need of changing the spring length, thereby saving the necessity of carrying an extensive stock of springs to meet the various requirements.

I accomplish these and other objects in the manner set forth in the following specifications as illustrated in the accompanying drawing, in which Fig. l is an elevation of a lift door installation as viewed from the inside of a garage,

Fig. 2 is a section taken along the line 22 in Fig. 1.

Fig. 3 is a section taken along the line 3-3 in Fig. 1.

Fig. 4 is a fragmentary view taken along the line 4-4 in Fig. 1.

Fig. 5 is a section taken along the line 5-5 in Fig. 4.

There is shown by way of example a garage door installation in which a plurality of panels are united by means of hinges 11 to form a complete door 12. The hinge pins 13 of the hinges 11 nearest the door edges 14 are each provided with a roller 15 which rolls in an upright track 16 which is joined by a curved portion 17 with a horizontal track portion 17-A. With this type of mechanism there is provided a single shaft 18 for each door 12. The shaft 18 is provided with suitable bearings 19 and 20,

On the outer end of each shaft 18 is secured a cable winding drum 21, whose cable 22 is attached to an anchor 23 at a lower corner of the door 12.

Power is applied to the drum 21 by an electric motor (not shown) either directly to the drum 21 or to the shaft 18 upon which the drum is secured, or it may be supplied manually through a handle 12-A provided on the lowermost panel 10.

Near each end of the shaft 18 is mounted a torsion spring 24 whose end 25 is attached to a bearing 19, while its end 26 is attached to an anchor collar 27 pinned on the shaft 18.

When the door 12 is raised either manually or with power, the spring 24 turns the shaft 18, which being in one piece, turns both of the drums 21 providing a uniform lifting effort at each lower corner of the door 12 The apparatus thus far disclosed is in common use.

Referring to my invention, it will be seen to consist of a sheet metal sleeve 28 placed over each spring 24, and around each sleeve 28 are placed a plurality of band clamps 29 whose overlapping portions are perforated to receive the thread 30 of a worm 31 mounted in the housing 32 and turned by a key 33 by means of which pressure on the sleeve 28 can be controlled to a nicety.

This makes it possible to have the sleeve 28 somewhat loose at the beginning of the door travel and set tight enough so that it can catch the spring about midway of the door travel. The relative setting of the clamps 29 makes it possible to conrol the performance of the spring throughout its operation. It is desirable to provide a lubricant such as parafiin between the springs 24 and the sleeves 28.

I claim:

1. In an overhead door lifting mechanism having a shaft with a cable drum adapted to make a plurality of revolutions in a door lifting movement, a torsion spring encircling said shaft and having one end anchored thereto, a flexible sleeve surrounding a portion of the length of said spring, and a pair of constricting clamping means operable on said sleeve at two axially spaced points, said clamping means being slidable toward and away from each other to vary the constricted length of said sleeve for adjusting the effective length of said spring at the end of the lifting movement of said shaft independent of the length of said spring at the beginning of the lifting movement of said shaft, and said clamping means being adjustable in diameter to vary the door position at which further expansion of the clamped length of said spring is prevented in a lifting movement.

2. In an overhead door lifting mechanism having a shaft with a cable drum adapted to make a plurality of revolutions in a door lifting movement, a torsion spring encircling said shaft and having one end anchored thereto, a flexible split sleeve surrounding a portion of the length of said spring, and a pair of band clamps on said sleeve, said clamps being slidable toward and away from each other to vary the effective spring length and provide fine adjustment of the spring force at the end of the lifting movement of said shaft independent of the spring force at the beginning of the lifting movement, and said clamps being adjustable in diameter to vary the door position at which further expansion of the adjusted length of spring between said clamps is prevented in a lifting movement.

References Cited in the file of this patent FOREIGN PATENTS 2,073,267 Prouty Mar. 9, 1937 2,257,484 Rowe Sept. 30, 1941 2,314,015 Parsons Mar. 16, 1943 

